Field of the Invention
The invention relates to a method and a device for rapidly measuring a large-area and massive scattered field in nanoscale.
Description of the Related Art
Conventional methods for measuring the three-dimensional profile parameters in IC manufacturing include: a scanning electron microscope (SEM), an atomic force microscope (AFM), a transmission electron microscopy (TEM), a conventional optical microscope (OM), an optical scattering device. The scanning electron microscope (SEM) and the transmission electron microscopy (TEM) are non-contact measurement and feature very high horizontal and vertical revolution. However, the samples are destructed during preparation for measurement, and it is impossible to conduct on-line and massive measurement due to limitation on a vacuum environment during measurement.
The atomic force microscope (AFM) is a kind of contact measurement using surface probes, but samples are easily destructed during measurement, and a scanning and measuring speed is comparatively slow. The conventional optical microscope (OM) cannot be used for measurement of nanometer-scale structure as being limited by optical revolution. The optical scattering device is referred to as an optical critical dimension (OCD) measurement instrument, a basic principle thereof is to project polarized light on surface of a measured structure, to obtain variation of a polarization state of the polarized light after reflection by measuring zeroth-order diffraction light of the measured structure, and to extract information of the measured structure by solving an inverse scattering problem.
However, as shown in FIG. 1, the conventional optical scattering device cannot collect diffraction light other than zeroth-order diffraction light of a measured sample, which makes information collection thereof incomplete. Since only reflection of the zeroth-order diffraction light with periodic structure is used, the device can only measure simple periodic structure with a small high-aspect-ratio deep structures (such as a one-dimensional grating structure and a two-dimensional grating structure) based on the current model-based measurement method. In addition, limited by spot size (a size of approximately 50 μm) during measurement, a few statistical parameters of the periodic structure, such as a critical dimension, a height, a side angle and so on, can be obtained within a range of the spot, which significantly restricts wider application of the optical scattering device, and makes it impossible to apply it to measurement of complex three-dimensional nanometer structure.